Promising new vaccines against West Nile Virus tested in rhesus monkeys

26 November 2014

The West Nile virus (WNV) is transmitted by mosquitoes. Especially in immunologically compromised individuals, the virus can cause severe disease such as meningitis. Worldwide, the number of WNV outbreaks in the human population is increasing. To date, there is no approved vaccine for use in humans.

Previous studies in mice have shown that vaccination with different experimental vaccines could protect against WNV. To test these vaccines in an animal model with an immune system that is very closely related to that of humans, BPRC researchers have tested the most promising candidates in rhesus monkeys.

During the experiment two different vaccine strategies were tested: a protein-vaccine and a protein-vaccine, in combination with a DNA-vaccine. Both vaccine components consisted of a part of the so-called envelope of the virus, the outer sheath, enabling recognition by the immune system. In order to increase the efficacy, the protein-vaccine was combined with Matrix-M, a substance which is extracted from the South American saponin tree, which has previously proved to be a good enhancing agent for vaccines.

The experiment showed that both vaccine strategies in combination with Matrix-M provided good protection to infection with WNV. In the control animals, the WNV was detected in the blood. This was in contrast to the vaccinated monkeys, in which the virus was not detected. This research, published in PlosOne, shows that it is possible to protect an animal species that is closely related to humans against WNV. This brings a vaccine against WNV in humans a significant step closer.